At 15° 56’ S and 5° 42’ W, the island of Saint Helena with its surface area of 122 km², was discovered by chance. Almost 2000 km from the coast of Africa and more than 3000 km from Brazil, in the middle of the high, which generates calms and light winds, this rock, which is now a British overseas territory could not be easily spotted, but during the third Portuguese expedition to the Indies, Captain João da Nova discovered first Ascension Island (1501) and then Saint Helena (21st May 1502) in the middle of nowhere.
On stepping ashore on this uninhabited island, he built a chapel and a few houses as a staging post for trading ships going between Europe and Asia. This influenced the route taken by these ships and the Portuguese introduced goats and planted lemon trees there. It became a stopover for fresh water and supplies, in particular citrus fruit, which thanks to their concentration of vitamin C, reduced the risk of scurvy, which seriously affected the crews on these long voyages.
In the middle of nowhere, a place of exile
In 1588, Sir Thomas Cavendish was the first British person to step ashore during his voyage around the world, the third after Fernando Magellan (1519-1522) and Francis Drake (1577-1580). Aboard Desire, this mercenary followed in the footsteps of his predecessor burning down three towns built by the Spanish and taking thirteen ships laden with gold for Elisabeth I. The discovery of Saint Helena enabled the English to stopover there to attack Portuguese ships returning from the east… In 1592, King Philip II of Spain ordered his fleet from Goa to avoid Saint Helena, which left it wide open for the Dutch to take possession in 1633. But they did not really colonise the island and left it to go to Cape Town.
The East Indies Company set up there and left some growers ashore in 1657 under the auspices of Richard Cromwell. Captain John Dutton’s fleet set up fortifications when the monarchy was restored in 1660, giving them the name of James Fort, while the nearby town was called Jamestown. This strategic point became the centre of several battles, as the Dutch East India Company took possession at Christmas 1672, forcing Governor Beale to head for Brazil to escape. He would regain control in May 1673 and set up a garrison of 250 soldiers, while Charles II declared Saint Helena “Part of England just like East Greenwich is part of Kent.” Not located on the trade winds route, the island was more or less left alone and the goats ravaged the forests and crops…
From Emperor to King…
Saint Helena became famous after the defeat of Napoleon at Waterloo on 18th June 1815, as he was sent into exile there by the British. The Emperor had managed to escape from Elba and needed to be kept away from his supporters. The British claimed the neighbouring island of Ascension to set up a naval garrison. Bonaparte died there in Longwood House on 5th May 1821 in mysterious circumstances thought possibly to have been a poisoning. He was buried on 9th May in Tomb Valley by the governor, Sir Hudson Lowe. King Louis-Philippe obtained the right to his ashes, which were brought back to France and kept at the Invalides in Paris. Napoléon III acquired the last resting place of his ancestor in 1858 and Tomb Valley was managed by the French Ministry of Foreign Affairs.
The Zulu king; Dinuzuluka Cetshwayo succeeded the Emperor as he was exiled there for seven years from 1890. In the second Boer War (1899-1902), the British Army transformed the island into a detention centre where more than 5000 prisoners were deported. Without a real harbour, the 4200 inhabitants are still very isolated with just one naval vessel, RMS St Helena bringing the Royal Mail and supplies from Cape Town. An airport was built, but the difficulty of landing there means that it has not been officially opened and there are no regular flights from South Africa.
Like the Azores in the North
In terms of the weather, Saint-Helena is as famous in the Southern Hemisphere as the Azores in the North Atlantic. An area of high pressure, which remains relatively stable throughout the year, is associated with both. In the Inter-Tropical Zone, the position of this high varies relatively little with each season, but it is influenced by areas of low pressure moving in and pushing it away or sometimes splitting it in two… While the Azores high is more volatile than its equivalent in the north, that is due to the surrounding relief and the importance of the ice caps in the North and South.
Pressure differences are down to temperature contrasts between the polar ice and the equatorial heat. As the Earth turns, it drags its atmosphere with it under the influence of the Coriolis effect (leading to a movement to the right in the Northern Hemisphere and left in the South), causing hot and cold air to come together smoothing out the world’s temperatures thanks to this exchange between high and low pressure areas.
A very mobile core
The Saint Helena high generates the counter-clockwise trade winds around this volcanic island, which is more or less at its core. The southerly flow along the coast of Africa (Namibia, Angola) backs SE’ly in the Gulf of Guinea and below the Doldrums and then easterly off Brazil and NW’ly around the islands of Trindade and westerly in the Forties. This huge movement meant that sailors coming from Europe and heading for India had to get around this area of high pressure via the west to avoid the calms which prevail near its core.
This is the route that the skippers in the eighth Vendée Globe will also probably have to take, as the centre of the high is currently very low down below South Africa and looks like splitting in two next week. To get around the Saint Helena high they will have to go a long way south. While the leaders may be able to hop onto an area of low pressure sweeping out of the Bay of Rio to make their way towards Gough Island, it is likely to be a different story for those chasing them.